Substrate processing apparatus and susceptor

ABSTRACT

A substrate processing apparatus includes a chamber, a susceptor to receive a substrate and provided in the chamber, a gas supply source to supply a predetermined gas into the chamber, and a high frequency power source to treat the substrate by plasma. The susceptor includes a first ceramics base member including a flow passage to let a coolant pass through, a first conductive layer formed on a principal surface and a side surface on a substrate receiving side of the first ceramics base member, and an electrostatic chuck stacked on the first conductive layer and configured to electrostatically attract the wafer received thereon. A volume of the flow passage is equal to or more than a volume of the first ceramics base member. The high frequency power source is configured to supply high frequency power to the first conductive layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based upon and claims the benefit of priorityof Japanese Patent Application No. 2013-10855, filed on Jan. 24, 2013,U.S. Provisional Patent Application No. 61/758,471, filed on Jan. 30,2013, Japanese Patent Application No. 2013-48172, filed on Mar. 11,2013, and U.S. Provisional Patent Application No. 61/783,597, filed onMar. 14, 2013, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus and asusceptor.

2. Description of the Related Art

In order to perform an intended microfabrication in a substrate,controlling a temperature of the substrate to keep the substrate at anappropriate temperature is important. Accordingly, it has been practicedto control the temperature of the substrate on a susceptor to set thesubstrate at an intended temperature by adjusting a temperature of thesusceptor by using a temperature controller such as chiller embedded inthe susceptor (see, for example, Japanese Laid-Open Patent ApplicationPublication No. 2005-57234).

The temperature of the substrate can be rapidly increased and decreasedby shortening time required to actually bring the susceptor to thecontrolled temperature in response to the temperature control of thesusceptor and by improving temperature responsiveness of the susceptor.

Major factors that enhance the temperature responsiveness of thesusceptor include heat capacity. When a base member of the susceptor ismade of aluminum or aluminum alloy, ensuring a mechanical strength ofthe susceptor is required by making the base member a predeterminedthickness or more. As a result, the base member weighs a predeterminedweight or more. When the weight of the base member is heavy, reducingthe heat capacity of the susceptor is difficult.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a novel and useful filmdeposition apparatus and film deposition method solving one or more ofthe problems discussed above.

More specifically, in response to the above-mentioned problem,embodiments of the present invention provide a substrate processingapparatus and a susceptor capable of improving temperatureresponsiveness of a susceptor.

According to one embodiment of the present invention, there is provideda substrate processing apparatus that includes a chamber, a susceptor toreceive a substrate and provided in the chamber, a gas supply source tosupply a predetermined gas into the chamber, and a high frequency powersource to treat the substrate by plasma. The susceptor includes a firstceramics base member including a flow passage to let a coolant passthrough, a first conductive layer formed on a principal surface and aside surface on a substrate receiving side of the first ceramics basemember, and an electrostatic chuck stacked on the first conductive layerand configured to electrostatically attract the wafer received thereon.A volume of the flow passage is equal to or more than a volume of thefirst ceramics base member. The high frequency power source isconfigured to supply high frequency power to the first conductive layer.

According to another embodiment of the present invention, there isprovided a susceptor that includes a first ceramics base memberincluding a flow passage to let a coolant pass through and formedtherein, a first conductive layer formed on a principal surface and aside surface on a substrate receiving side of the first ceramics basemember, and an electrostatic chuck stacked on the first conductive layerand configured to electrostatically attract a substrate placed thereon.A volume of the flow passage is equal to or more than a volume of thefirst ceramics base member.

Additional objects and advantages of the embodiments are set forth inpart in the description which follows, and in part will become obviousfrom the description, or may be learned by practice of the invention.The objects and advantages of the invention will be realized andattained by means of the elements and combinations particularly pointedout in the appended claims. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory and are not restrictive of the invention asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional side view illustrating an etchingprocessing apparatus according to an embodiment;

FIG. 2 is a view for explaining a roll compaction method utilized formanufacturing a susceptor according to an embodiment;

FIG. 3 is a view illustrating an example of manufacturing a susceptoraccording to an embodiment using the roll compaction method;

FIG. 4 is a table comparing a physical property of a base member made ofSiC according to an embodiment with that of a base member made of Al;

FIG. 5 is a configuration diagram of a cooling mechanism used in anexperiment of temperature responsiveness of a susceptor according to anembodiment;

FIG. 6 is a graph illustrating an example of an experiment result oftemperature responsiveness according to an embodiment;

FIG. 7 is a graph illustrating another example of the experiment resultof temperature responsiveness according to an embodiment;

FIG. 8 is a table comparing a flow passage cubic volume of a base membermade of SiC according to an embodiment with that of a base member madeof Al;

FIG. 9 is a vertical cross-sectional view of a suspector according to anembodiment;

FIG. 10 is an enlarged view of an outer edge portion of a susceptoraccording to an embodiment;

FIG. 11 is an enlarged view of an outer edge portion of an upperelectrode according to an embodiment;

FIG. 12 is a graph comparing a skin depth of a sprayed film made of Alaccording to an embodiment with that of a base member made of Al and;

FIGS. 13A and 13B are views illustrating a groove portion provided in abase member made of SiC according to an embodiment;

FIGS. 14A and 14B are views illustrating a sprayed film made of Alformed on a base member made of SiC according to an embodiment; and

FIG. 15 is a view comparing relationships between a configuration of asusceptor and a matching point according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description is given below of an embodiment of the present invention,with reference to the drawings. In the present specification and thedrawings, with respect to the substantially same configuration,overlapped descriptions are omitted by attaching the same numerals.

[Etching Processing Apparatus]

To begin with, a description is given below of an example of an etchingprocessing apparatus of an embodiment of the present invention withreference to FIG. 1. FIG. 1 is a vertical cross-sectional view of alower-part-two-frequency-application-type parallel plate etchingprocessing apparatus in a parallel plate plasma apparatus.

An etching processing apparatus 10 keeps its inside sealed and includesa chamber C electrically grounded. The chamber C has a cylindricalshape, and for example, is made of aluminum whose surface is anodized. Asusceptor 100 is provided that supports a silicon wafer W (which ishereinafter just called a “wafer W”) inside the chamber C. A base member100 a of the susceptor 100 is made of silicon carbide (SiC). Thesusceptor 100 is supported by a support 104 through a clamp 101 by usinga screw 101 a. The support 104 is made of aluminum. The susceptor 100also functions as a lower electrode. Here, the base member 100 a of thesusceptor 100 corresponds to a first ceramics base member.

The susceptor 100 can be moved up and down by an elevating mechanism 107through an insulating plate 103. The elevating mechanism 107 is coveredwith a bellows 108 that connects the bottom of the chamber C with theinsulating plate 103. The bellows 108 is made of stainless steel. Abellows cover 109 is provided outside the bellows 108.

A focus ring 105 is provided on an outer periphery of the susceptor 100.The focus ring 105 is made of silicon (Si). A cylindrically shaped innerwall member 103 a, which is, for example, made of quartz, is provided onan outer circumference of the susceptor 100, the support 104 and thefocus ring 105.

An electrostatic chuck 106 to electrostatically attract the wafer W isprovided on an upper surface of the susceptor 100. The electrostaticchuck 106 has a structure having a chuck electrode 106 a embedded in aninsulating plate 106 b. The insulating plate 106 b is, for example, madeof alumina (Al₂O₃). A direct voltage source 112 is connected to thechuck electrode 106 b. When a direct voltage is applied to the chuckelectrode 106 a from the direct voltage source 112, the wafer W isattracted on the electrostatic chuck 106 by a coulomb force.

A flow passage 102 is formed inside the susceptor 100. The flow passage102 is connected to a cooling mechanism 102 a through pipes 102 b. Thecooling mechanism 102 a serves to adjust the wafer W to a predeterminedtemperature by allowing a coolant such as propene, 1,1,2,3,3,3,-hexafluoro-, oxidized, polymd (Galden™) and cooling water to flowthrough the pipes 102 b and by circulating the coolant in the flowpassage 102. A heat transfer gas supply source 85 supplies a heattransfer gas such as a helium gas (He) and an argon gas (Ar) to a backsurface of the wafer W on the electrostatic chuck 106 through a gassupply line 113.

Transfer of the wafer W is performed by moving pins 81 that support thewafer W up and down. The pins 81 are connected to a drive mechanism 84through a coupling member 82. The pins 81 move up and down by a drivingforce of the drive mechanism 84, and support the wafer W by penetratingthrough-holes 100 a provided in the susceptor 100.

A first high frequency power source 110 a is connected to the susceptor100 through a first matching box 111 a. The first high frequency powersource 110 a, for example, supplies high frequency power of 40 MHz forplasma generation to the susceptor 100. Moreover, a second matching boxis connected to the susceptor 100 through a second high frequency powersource 110 b. The second high frequency power source 110 b, for example,supplies high frequency power for bias of 3.2 MHz to the susceptor 100.

A shower head 116 is provided facing the susceptor 100, above andbetween the susceptor 100 and a ceiling portion of the chamber C. Theshower head 116 is supported by a side wall of the chamber C through aninsulating member 145. By this structure, the shower head 116 thatfunctions as the upper electrode and the susceptor 100 that functions asthe lower electrode form a pair of electrode structure.

The shower head 116 includes a body part 116 a and an upper ceilingplate 116 b that forms an electrode plate. The body part 116 a is madeof a conductive material, for example, aluminum whose surface isanodized, and supports the upper ceiling plate 116 b on its lowersurface detachably.

A diffusion chamber 126 a of gas is provided inside the body part 116 a.The diffusion chamber 126 a is communicated with many gas pipes 116 dand introduces a gas into gas introduction holes 116 e.

A gas introduction port 116 g to introduce a gas into the diffusionchamber 126 a is formed in the body part 116 a. A gas supply source 120is connected to the gas introduction port 116 g. The gas supply source120 supplies an etching gas during the process. The etching gas suppliedfrom the gas supply source 120 to the diffusion chamber 126 a isintroduced to a plasma processing space in the chamber C in a form of ashower through the gas pipes 116 d and the gas introduction holes 116 e.

A lid body 114 of a cylindrical shape is provided so as to extend fromthe side wall of the chamber C to a position higher than a heightposition of the shower head 116. The lid body 114 is a conductor andgrounded. An exhaust port 171 is formed in the bottom of the chamber C.An exhaust device 173 is connected to the exhaust port 171. The exhaustdevice 173 includes a vacuum pump not shown in the drawing, and reducesa pressure in the chamber C up to a predetermined degree of vacuum. Adipole ring magnet 124 that circularly or concentrically extends isarranged at an outer circumference of the chamber C.

By this configuration, an RF (Radio Frequency) electric field is formedin a vertical direction in a space between the susceptor 100 and theshower head 116 by a first high frequency power source 110 a, and ahorizontal magnetic field is formed by the dipole ring magnet 124.High-density plasma is generated in the vicinity of the surface of thesusceptor 100 by a magnetron discharge using these orthogonal electricand magnetic fields.

A control device 200 controls each part attached to the etchingprocessing apparatus 10 such as the gas supply source 120, the exhaustdevice 173, the high frequency power sources 110 a, 110 b, the matchingboxes 111 a, 111 b, the direct voltage source 112, the drive mechanism84, and the heat transfer gas supply source 85.

The control device 200 includes a CPU (Central Processing Unit) 200 a, aROM (Read Only Memory) 200 b, and a RAM (Random Access Memory) 200 c.The CPU 200 a executes a plasma treatment in accordance with variousrecipes stored in the ROM 200 b or the RAM 200 c. The recipes containapparatus control information in response to process conditions such asa process time, a temperature in the chamber (upper electrodetemperature, side wall temperature of the chamber, ESC temperature andso on), a pressure (of gas exhaustion), high frequency power andvoltage, various process gas flow rates, a heat transfer flow rate. Asdiscussed above, a description was given of a whole configuration of theetching processing apparatus 10 of the present embodiment.

[Method of Manufacturing Susceptor]

Next, a description is given below of a method of manufacturing asusceptor provided in an etching processing apparatus according to anembodiment of the present invention, with reference to FIGS. 2 and 3.FIG. 2 is a view for explaining a roll compaction (RC) method used formanufacturing a susceptor 100 of an embodiment. FIG. 3 is a viewillustrating an example of manufacturing the susceptor 100 of anembodiment, using the roll compaction method.

In the roll compaction method used for manufacturing the susceptor 100of the present embodiment, powder of silicon and carbon (C) that arematerials to manufacture a base member of silicon carbide (which ishereinafter expressed as SiC) are input to a container 250 at anintended blend ratio. The container 250 produces slurry A by mixing theinput materials. The slurry A is ejected in the form of a line from afeeder 260 (see B in FIG. 2) and compressed by two rotating mill rolls270, by which a ceramics sheet of SiC is formed.

The ceramics sheet of SiC is formed into an intended shape by a laserprocess. For example, FIG. 3 illustrates nine ceramics sheets Sa throughSi in a state of having been processed by a laser respectively. Holes tolet the pins 81 pass through are formed in the ceramics sheets Sa, Sb,Sh and Si. Moreover, spiral flow passages are formed in the ceramicssheets Sc through Sg. The nine ceramics sheets Sa through Si arelaminated by applying an adhesive between the respective sheets, inputinto a treatment furnace, and fired integrally. By doing this, the basemember of the susceptor 100 of the present embodiment is formed. Thebase member of the susceptor 100 of the present embodiment can be firedquickly because the base member is not made of a bulk material but has alaminate structure made from thin sheet materials, by which operatingtime of the treatment furnace can be reduced. Furthermore, a hollowstructure such as a flow passage 102 can be formed in a seamless mannerdue to the integration firing. With respect to the structure of the flowpassage 102 and the like, various shapes can be flexibly formed byutilizing the laser process. In addition, because particles are bondedby solid phase sintering, the strength of the base member of SiC is asmuch as the bulk material or more.

There is an index including Young's modulus and a bending strength toshow the strength of materials. Young's modulus is an amount ofdisplacement when a certain force is applied, and is 450 PGa when thebase member is made of SiC manufactured by the roll compaction method,while it is 70 GPa when the base member is made of aluminum (which ishereinafter expressed as Al).

The bending strength is a maximum bending stress caused before a crack,a breach or a fracture occurred in a test piece, and is 430 MPa when thebase member is made of SiC, relative to 200 MPa when the base member ismade of Al.

As discussed above, it is noted that the base member of SiC is superiorto the base member of Al in mechanical strength. Accordingly, thesusceptor 100 including the base member of SiC has a mechanical strengththat can withstand a vacuum load in the chamber C and an inner pressurefrom the coolant flowing through the flow passage 102 formed inside thebase member 100 a.

In addition, the base member 100 a used in the susceptor 100 of thepresent embodiment excels in temperature responsiveness. In order toimprove the temperature responsiveness, it is favorable to decrease heatcapacity and to increase a thermal diffusion factor (i.e., thermalconductivity of the susceptor). The heat capacitor is determined by ρ(density)×V (volume)×Cp (specific heat) [J/K]. The thermal diffusionfactor is determined by k/(ρ×Cp) [m²/s].

Referring to the comparison of the physical property between the basemember of SiC and the base member of Al shown in FIG. 4, the heatcapacity calculated by multiplication of the weight (=ρ×V) and thespecific heat is 800 [J/K] in the base member of SiC, relative to 4500[J/K] in the base member of Al.

Moreover, the thermal diffusion factor is 90×10⁻⁶ [m²/s] in the basemember of SiC, relative to 70×10⁻⁶ [m²/s] in the base member of Al.

As discussed above, in the present embodiment, the base member 100 a ofSiC manufactured by the roll compaction method is used in the susceptor100. This makes it possible to decrease the heat capacity of the basemember 100 a by reducing weight, thickness and size of the base member100 a while maintaining the mechanical strength of the base member 100a. As a result, the temperature responsiveness of the susceptor 100 canbe enhanced.

[Experiment of Temperature Responsiveness]

Next, an experiment relating to the temperature responsiveness of thesusceptor is performed when the base member of SiC and the base memberof Al are used. FIG. 5 is a configuration diagram of a cooling mechanismused in the experiment of the temperature responsiveness of thesusceptor.

The cooling mechanism 102 a switches the coolant supplied from a firstcontainer 102 a 1 that stores the coolant of 80° C. and a secondcontainer 102 a 2 that stores the coolant of 20° C., and lets thecoolant flow through the flow passage 102 of the susceptor 100. Theswitching of the coolant supplying to the susceptor 100 is performed byswitching three-way valves TV1, TV2 and valves V1, V2. A flow meter Fmeasures a flow rate of the coolant flowing through the pipe. Thesusceptor 100 is placed in the chamber C of a predetermined vacuumatmosphere. Pressure gauges P1, P2 are attached to the inlet and outletof the flow passage 102 formed in the susceptor 102. Temperature sensorsTC1, TC2 and TC3 of thermocouples are respectively attached to the inletof the flow passage 102, the upper portion of the base member of thesusceptor 100 (i.e., receiving surface of the wafer W) and the outlet ofthe flow passage 102.

FIG. 6 shows a result of the temperature responsiveness when thetemperature of the coolant is switched from 20° C. to 80° C. in usingthe experimental system having the above configuration, and FIG. 7 showsa result of the temperature responsiveness when the temperature of thecoolant is switched from 20° C. to 80° C.

Horizontal axes in FIGS. 6 and 7 indicate time [s], and vertical axesindicate a temperature [° C.]. To begin with, a description is givenbelow with reference to the case of switching from the coolant of 20° C.to the coolant of 80° C. shown in FIG. 6. The first two seconds indicatetime from when the three-way valves TV1, TV2 and the valves V1, V2 wereswitched till when the coolant of 80° C. after the switching reached thepositions where the temperature sensors TC1 through TC3 were attached.Hence, the actual start time for measuring the temperatureresponsiveness is two seconds later from the switching of the valves andthe like. Here, when the coolant was switched from 20° C. to 80° C.,because the coolants of 20° C. and 80° C. intermingle with each other inthe pipe, the temperature does not become 80° C. immediately. In thisexperiment, an attainment temperature of the base member of thesusceptor 100 is set at 70° C.

The base member of the susceptor 100 of the present embodiment is madeof SiC. In this case, the temperature detected by the temperature sensorTC1 of the inlet of the flow passage 102 (TC1 (INLET, SiC) in FIG. 6)firstly reaches 70° C. The time was 6.5 seconds when the temperaturedetected by the temperature sensor TC2 (TC2 (SiC BASE MEMBER) in FIG. 6)on the upper portion of the base member of the susceptor 100 and thetemperature sensor TC3 (TC3 (OUTLET, Al) in FIG. 6) of the outlet of theflow passage 102 reached 70° C. At this time, the increase intemperature detected by the temperature sensor TC2 of SiC on the upperportion of the base member was about 7.7° C./second.

On the other hand, when the base member of the susceptor is made of Al,the temperature detected by the temperature sensor TC1 of the inlet ofthe flow passage 102 (TC1 (INLET, SiC) in FIG. 6) also firstly reaches70° C. The time was 30.5 seconds when the temperature detected by thetemperature sensor TC2 (TC2 (SiC BASE MEMBER) in FIG. 6) on the upperportion of the base member of the susceptor 100 and the temperaturesensor TC3 (TC3 (OUTLET, Al) in FIG. 6) of the outlet of the flowpassage 102 reached 70° C. At this time, the increase in temperaturedetected by the temperature sensor TC2 of SiC on the upper portion ofthe base member was about 1.64° C./second.

The above experimental result proved that the temperature responsivenessof the susceptor in increasing the temperature from 20° C. to 70° C.improved about 4.7 times as much as the case of using Al as the basemember when SiC was used as the base member.

Considering the experimental result, the heat capacity of the basemember made of Al is high. Accordingly, the base member of Al cannotrapidly increase and decrease the temperature thereof following thetemperature change, even when the coolant is changed, and thetemperature responsiveness is insufficient.

More specifically, in a case of the base member of Al, because the heatcapacity of the base member of Al is high, the heat of the coolant doesnot immediately transfer to the base member of Al. As a result, much ofthe heat of the coolant reaches the outlet of the flow passage beforedrawn by the base member at the beginning of changing the temperature.Hence, the temperatures respectively detected by the temperature sensorTC1 at the inlet of the flow passage of the susceptor and thetemperature sensor TC3 at the outlet of the flow passage become higherthan the temperature detected by the temperature sensor TC2 at the upperportion of the susceptor on ahead, and the temperature detected by thetemperature sensor TC2 at the upper portion of the susceptor does notincrease immediately.

In contrast, in a case of the base member of SiC, because the heatcapacity of the base member made of SiC is low, the heat of the coolantin the flow passage 102 of the susceptor is easy to be drawn by the basemember. As a result, the temperature that the temperature sensor TC2 hasdetected at the upper portion of the susceptor shifts in the same way asthe temperatures respectively detected by the temperature sensor TC1 atthe inlet of the flow passage of the susceptor 100 and the temperaturesensor TC3 at the outlet of the flow passage, and the preferabletemperature responsiveness can be obtained.

The experimental result in FIG. 7 is considered similarly. When thecoolant of 80° C. was switched to the coolant of 20° C., because thecoolants of 80° C. and 20° C. were mixed with each other in the pipe,the temperature did not become 20° C. immediately. In this experiment,the attainment temperature of the base member of the susceptor was setat 30° C.

In a case of the susceptor 100 of the base member made of SiC, the timebefore the temperature detected by the temperature sensor TC2 (TC2 (SiCBASE MEMBER) in FIG. 7) at the upper portion of the base member of thesusceptor reaches 30° C. was 6.3 seconds. At this time, the decrease intemperature detected by the temperature sensor TC2 at the upper portionof the susceptor 100 was about 7.9° C./second.

By contrast, when the base member of the susceptor was made of Al, thetime before the temperature sensor TC2 (TC2 (Al BASE MEMBER) in FIG. 7)at the upper portion of the base member of the susceptor reached 30° C.was 36 seconds. The decrease in temperature was about 1.39° C./second.

The above experimental result proved that the temperature responsivenessin decreasing the temperature from 80° C. to 30° C. improved about 5.7times as much as the case of the base member made of Al when SiC wasused as the base member.

[Volume Ratio of Flow Passage Relative to Volume of Base Member]

Next, a description is given below of a volume ratio of the flow passagerelative to a volume of the base member with reference to FIG. 8. FIG. 8is a table comparing a volume ratio of the flow passage 102 relative toa volume of the base member of SiC of the susceptor 100 of the presentembodiment with that of a case of the base member of Al.

The whole volume shown in the table is a summation of the volume of thebase member and the volume of the flow passage of the base member.According to this, the whole volume when the base member 100 a of SiC isused in the susceptor 100 like the present embodiment becomes about ⅓ ofthe whole volume when Al is used as the base member. Moreover, when thebase member of SiC is used, the volume of the flow passage 102 can bemore than the volume of the base member of SiC. In other words, the flowpassage volume ratio relative to the whole volume is 50% or more. Whenthe base member of SiC is used, the volume of the flow passage 102 ispreferably 1 through 1.4 times as much as the volume of the base memberof SiC. In other words, the flow passage volume ratio relative to thewhole volume is preferably 50 through 70%.

On the other hand, because the whole volume when Al is used as the basemember in the susceptor is about three times as much as the whole volumewhen SiC is used as the base member, it is substantially impossible tomake the flow passage volume ratio 50% or more while maintaining themechanical strength. In FIG. 8, when Al is used as the base member, theflow passage volume ratio relative to the whole volume is 25%. Here,when the base member is made of alumina (Al₂O₃), because the strengthcannot be maintained if the thickness of the base member is made thin,it is also impossible to make the flow passage volume ratio relative tothe whole volume 50% or more.

In this manner, by setting the volume ratio of the flow passage 102relative to the whole volume in the base member 100 a of SiC at 50% ormore, the susceptor 100 of the present embodiment can be formed to havea structure easy to transfer the temperature of the coolant flowingthrough the flow passage 102 to the wafer W on the susceptor 100. Thismakes it possible to enhance the temperature responsiveness of thesusceptor 100, to reduce the time before the susceptor 100 actuallybecomes the controlled temperature in response to the temperaturecontrol of the susceptor 100, and to rapidly change the temperature ofthe wafer W.

[Structure of Susceptor]

Next, a description is given below of a structure of the susceptor 100of the present embodiment with reference to FIGS. 9 and 10. FIG. 9 is avertical cross-sectional view of the susceptor 100 of the presentembodiment. FIG. 10 is a vertical cross-sectional view of an outerperipheral portion of the susceptor 100 of the present embodiment.

High frequency power is supplied to the susceptor 100, and the susceptor100 functions as a lower electrode. Here, as discussed above, the basemember 100 a of the susceptor 100 is made of SiC. When a ceramics basemember such as SiC is used in the susceptor 100, the ceramics does notconduct electricity. Therefore, in the present embodiment, by sprayingAl on the base member 100 a of the susceptor 100, a conductive layer 100b is formed, and the high frequency power is applied to the conductivelayer 100 b. More specifically, the conductive layer 100 b is formed onat least the principal surface and the side surface on the side on whichthe wafer W is placed of the base member 100 a of SiC, and is configuredto become the lower electrode when the high frequency power is supplied.Here, the conductive layer 100 b corresponds to a first conductive layerformed on the principal surface and the side surface on the side onwhich the substrate is placed of the first ceramics base member.

As illustrated in FIG. 10, two step portions are formed in the principalsurface at the outer periphery of the susceptor 100 in a circumferentialdirection. A first step portion 100 a 1 is formed on the outer side, anda second step portion 100 a 2 is formed on the inner side. The principalsurface of the base member 100 a of SiC may be the whole surface of thereceiving surface 100 a 3 of the wafer W defined by the first stepportion 100 a 1 and the second step portion 100 a 2. Moreover, the sidesurface of the base member 100 a of SiC may be a surface of a side walldefined by the first step portion 100 a 1 and the second step portion100 a 2. Here, the first step portion 100 a 1 and the second stepportion 100 a 2 are an example of a step portion provided in theperiphery of the susceptor 100 a.

A spiral tube 300 is provided on the side surface of the outermostperiphery of the base member 100 a of the susceptor 100. The spiral tube300 is formed of a conductive material having a reactive force. Thespiral tube 300 electrically connects the conductive layer 100 b withthe support 104 and absorbs a force from the horizontal direction.

Forming a screw hole in the ceramics base member 100 a such as SiC isdifficult. Accordingly, a clamp 101 that engages with the first stepportion 100 a 1 of the susceptor 100 through a rubber member 310 isprovided on the outer circumference of the susceptor 100, and a screwhole is formed in the clamp 101. The base member 100 a is fixed to thesupport 104 by a screw 101 a inserted in the screw hole through theclamp 101.

A rubber member 305 is formed of an O-ring and the like, arranged on theback surface of the base member 100 a, and seals a vacuum space in thechamber C from the atmosphere. The rubber member 305 is an elastic body,formed of silicon system resin, and functions as a cushion member infixing the base member 100 a to the support 104 by absorbing a forcefrom a vertical direction to the base member 100 a.

Here, by forming the conductive layer 100 b on the back surface of thebase member 100 a, and by arranging the spiral tube 300 on the backsurface of the base member 100 a instead of the rubber member 305, theconductive layer 100 b may be connected with the support 104 on the backsurface of the base member 100 a.

The base member 100 a of SiC has low wettability. Hence, it is difficultto directly form an insulating layer of alumina on the base member 100 aof SiC by thermal spray. Therefore, the conductive layer 100 b is formedon the base member 100 a by spraying aluminum. The conductive layer 100b may be a sprayed coating of tungsten (W).

After that, the insulating layer 106 b of the electrostatic chuck 106 isformed by spraying alumina on the conductive layer 100 b. Moreover, thechuck electrode 106 a of the electrostatic chuck 106 is formed byspraying tungsten (W) thereon. Furthermore, by spraying alumina thereon,the electrostatic chuck 106 that sandwiches the chuck electrode 106 abetween the insulating layers 106 b is formed. When the electrostaticchuck 106 is formed by sprayed coating, because an adhesive is notneeded between the conductive layer 100 b and the insulating layer 106b, the electrostatic chuck 106 is unlikely to be damaged during awaferless dry cleaning (WLDC). In addition, a thermal expansioncoefficient of the insulating layer 106 b of the electrostatic chuck 106formed of the sprayed coating can be approximated to that of the basemember 100 a of SiC. This makes it possible to manufacture the susceptor100 in which the electrostatic chuck 106 is unlikely to release from thebase member 110 a.

As illustrated by FIGS. 9 and 10, a diameter of the receiving surface100 a 3 of the wafer W is smaller than that of the wafer W. Accordingly,the periphery of the wafer W placed on the receiving surface 100 a 3protrudes from the receiving surface 100 a 3, and positions above thesecond step portion 100 a 2. Through holes 100 d to let the pins 81 forsupporting the wafer W pass through are formed in the base member 100 aat positions that penetrate the second step portion 100 a 2. Cutoutportions or through holes are provided in the focus ring 105.

When the wafer W is carried, the pins 81 penetrate the through holes 100d and contact the lower surface of the periphery of the wafer W.According to this structure, because the pins 81 support the peripheryof the wafer W, the through holes 100 d are not formed in the vicinityof the central portion of the wafer W. When there is a through-holeportion in the vicinity of the central portion of the wafer W, thetemperature of the wafer W located at the through-hole portion and thesurroundings thereof is not cooled but becomes high temperature (whichis so-called a “hot spot”). Like the present embodiment, by arrangingthe pins 81 in the periphery, the generation of the hot spot can beprevented.

A path for supplying helium (He) may be formed in the ceramics sheet Sillustrated in FIGS. 2 and 3. With this, as illustrated in FIG. 9, a gassupply line 113 can be formed. A sleeve 113 a formed by sinteringalumina is fitted in the gas supply line 113. This can prevent anabnormal discharge from occurring in the gas supply line 113. Paths 113b for supplying helium (He) connected to the gas supply line 113 areformed in the insulating layer 106 b of the conductive layer 100 b andthe electrostatic chuck 106 in a net-like manner.

At least a part of the flow passage 102 is formed in the base member 100a in a portion overlapping the focus ring 105 when seen from a planarperspective in a stacking direction of the focus ring 105 and the basemember 100 a on the second step portion 100 a 2. This improves the heatconduction of the focus ring 105. In this manner, the susceptor 100using the base member of SiC can be manufactured.

The following method can be provided as another method of manufacturingthe susceptor 100 using the base member 100 a of SiC. First, theconductive layer 100 b is formed by spraying aluminum on the base member100 a of SiC, and then alumina is sprayed thereon. The insulating layerof the electrostatic chuck is not sprayed, but an insulating plate-likemember is stuck on the sprayed alumina layer by an adhesive. The processof spraying alumina may be omitted when the alumina layer can bereplaced by the adhesive. Moreover, alumina is sprayed on the uppersurface of the insulating plate-like member. Basically, the path 113 bfor supplying helium (He) is formed in the plate-like member. Accordingto the plurality of methods of manufacturing the susceptor 100 describedabove, the electrostatic chuck 106 is stacked on the conductive layer100 b through the sprayed coating or the adhesive layer.

[Shower Head (Upper Electrode)]

As illustrated in FIG. 1, the shower head 116 is provided at a positionfacing the susceptor 100 in the chamber C, and functions as an upperelectrode. The shower head 116 of the present embodiment may have aconfiguration other than the configuration illustrated in FIG. 1, forexample, a configuration similar to the susceptor 100 that alsofunctions as a lower electrode.

More specifically, as illustrated in FIG. 11, the body part 116 a of theshower head 116 and an upper ceiling plate 116 b may be formed of a basemember 200 a of SiC. In this case, the base member 200 a corresponds toa second ceramics base member.

The conductive layer 200 b is formed on a principal surface 200 a 2(upper surface in FIG. 11) on the opposite side of a surface 200 a 1(lower surface in FIG. 11) facing the susceptor 100 of the base member200 a of SiC and on a side surface. The conductive layer 200 b may be asprayed coating of aluminum or a sprayed coating of tungsten. Theconductive layer 200 b corresponds to a second conductive layer. Thebase member 200 a of SiC is made of SiC whose plasma resistance propertyis higher than that of silicon (Si) or carbon (C), and is exposed to theplasma generation space side. Thus, the conductive layer 200 b thatbecomes an electrode layer of the upper electrode is provided byspraying aluminum on the principal surface (back surface) 200 a of thebase member 200 a of SiC and the side surface, but is not provided onthe surface exposed to the plasma. This can prevent metal contamination.

The shower head 116 is supported by a grounded supporting member 405that is made of aluminum. A spiral tube 400 is provided on the outermostperipheral side surface of the base member 200 a of SiC. The spiral tube400 is made of a conductive material having a reaction force. The spiraltube 400 electrically connects the conductive layer 100 b with thesupporting member 405 and absorbs a force from a horizontal direction tothe base member 200 a. With this, the conductive layer 100 b functionsas a conductive layer of the upper electrode.

Here, the base member 200 a of SiC may be manufactured by rollcompaction method as well as the base member 100 a of SiC in thesusceptor 100.

[Skin Depth]

The high frequency power is supplied to at least one of the conductivelayer 100 b of the susceptor 100 and the conductive layer 200 b of theshower head 116. When the high frequency power is applied to theconductive layer 100 b or the conductive layer 200 b, the current passesalong the surface of the conductive layer 100 b or the conductive layer200 b. A phenomenon that a current concentrates more greatly to asurface of a conductive layer as a frequency of high frequency powerbecomes higher is called a skin effect, and a depth through which acurrent flows is called a skin depth.

FIG. 12 is a graph comparing a skin depth of a base member (bulk) ofaluminum with that of a sprayed coating of aluminum. The horizontal axisindicates a frequency (kHz), and the vertical axis indicates a skindepth (μm). This graph shows that the skin depth of the base member ofaluminum is lower than that of the sprayed coating of aluminum in thesame frequency. More specifically, the graph shows that the base memberof aluminum can conduct a current more efficiently than the sprayedcoating of aluminum and even a thin member does not harm the propertywhen the frequency is the same. This means that the sprayed coating doesnot conduct a current efficiently because a degree of purity and adegree of density of the sprayed coating are lower than those of thebase member of aluminum. Accordingly, it is noted that the sprayedcoating of aluminum is required to be thicker than the base member ofaluminum and the electricity does not conduct efficiently when theconductive layer 100 b and the conductive layer 200 b are too thin.

Considering the above discussion, in the present embodiment, thethicknesses of the conductive layer 100 b and the conductive layer 200 bare determined based on a volume resitivity and a frequency of a highfrequency power used in the etching processing apparatus 10. Morespecifically, it is only necessary that the thicknesses of theconductive layer 100 b and the conductive layer 200 b are more than theskin depth determined depending on the frequency of the high frequencypower. For example, in the etching processing apparatus 10, the utilizedfrequency of the high frequency power is a predetermined value in arange from 400 kHz to 100 MHz. Accordingly, the thicknesses of theconductive layer 100 b and the conductive layer 200 b may be set atpredetermined thicknesses in a range from 20 μm to 300 μm correspondingto this frequency band in FIG. 12.

Moreover, it is only necessary that the volume resistivities of theconductive layer 100 b and the conductive layer 200 b by sprayed coatingof aluminum may be both 5×10⁻⁵ or less. Furthermore, in the conductivelayer 100 b and the conductive layer 200 b by sprayed coating ofaluminum, it is only necessary to manage the thicknesses in a range from0 to 10%. Here, the volume resitivity of the base member of aluminum is2×10⁻⁶Ω or less.

[Method of Thermal Spray]

Next, a description is given below of a method of thermal spray ofaluminum in order to deposit the conductive layer 100 b and theconductive layer 200 b at predetermined thicknesses in a range from 20μm to 300 μm with reference to FIGS. 13 and 14. Here, a description isgiven by citing the base member 100 a of the susceptor 100, but thedescription can be applied to the base member 200 a of the shower head116.

FIG. 13A is a perspective view illustrating a part of the base member100 a. FIG. 13B is a view providing a plurality of groove portions inthe step portion of the base member 100 a in FIG. 13A. FIG. 14A is across-sectional view and a plan view when a sprayed coating of aluminumis formed on the base member 100 a in FIG. 13A. FIG. 14B is across-sectional view and a plan view when a sprayed coating of aluminumis formed on the base member 100 a in FIG. 13B.

In a process of forming the sprayed coating 100 b of aluminum on thebase member 100 a by thermal splay, as illustrated in FIG. 14A, thethickness of the sprayed coating 100 b may become thin, or may becomedifficult to be sprayed on step portions Q1, R1 and S1 of the basemember 100 a. In other words, electricity does not flow efficiently atthe position Q1, R1 and S1, where the coating is likely to release fromthe base member 100 a because the coating is thin and fragile.

Therefore, in the method of thermal spray of the present embodiment, asillustrated in FIG. 13B, in the step portions Q2, R2 and S2, a pluralityof groove portions 100 e is regionally formed from the flat centralportion of the base member 100 a to the outside, and then the sprayedcoating is formed by spraying aluminum. In FIG. 13B, in the stepportions Q2, R2 and S2 of the periphery of the base member 100 a, theplurality of groove portions is formed in a circumferential direction.The step portions Q2, R2 and S2 are planarized in regions in the grooveportions 100 e.

This allows the sprayed aluminum to be easily collected in the grooveportions 100 e at the periphery of the base member 100 a. This makes itpossible to ensure the thickness of 20 μm to 300 μm at least in thegroove portions 100 e even if the thickness of the sprayed coating 100 bbecomes thin in the circumferential direction at the step portions Q2,R2 and S2. This can prevent the sprayed coating 100 b of aluminum frombeing thin in the circumferential direction as a whole at the stepportions Q2, R2 and S2.

According to this structure, the groove portions 100 e function as pathsto let the current through the sprayed coating of aluminum. This allowsthe current to easily pass through the sprayed coating 100 b. Moreover,the groove portions 100 e have a function of preventing the sprayedcoating from being released.

As discussed above, according to the method of thermal spray of thepresent embodiment, the sprayed coating 100 b of aluminum that easilyconducts the current and makes it difficult to be stripped off can beformed. According to this method, a path for a current is not requiredto be formed by metal processing tool, but can be formed on the surfaceof the base member. Here, in forming the groove portions 100 e in thebase member 100 a, by making a special tool, the process is made easyand the cost can be reduced. Here, the step portion of the ceramics basemember may include the plurality of groove portions.

[Confirmatory Experiment of Current Flow]

Finally, a description is given below of an experiment to confirm astate of a current when a wafer W of 300 mm was placed on variouselectrodes with reference to FIG. 15. The compared electrodes were thefollowing three kinds of electrodes.

<Compared Electrodes>

-   -   1. An electrode of a base member (bulk) of Al    -   2. An electrode on which Al was sprayed on a base member of SiC    -   3. An electrode without sprayed Al on a bases member of SiC

Moreover, process conditions of the experiment were as follows.

<Process Conditions>

Pressure 39 mTorr (4.000 Pa) Kind of Gas/Gas Flow Rate O₂/200 sccm HighFrequency Power/Power 100 MHz (First High Frequency Power Source)/2400 WHigh Frequency Power/Power 13.56 MHz (Second High Frequency PowerSource)/0 W

Based on the above process conditions, in the etching processingapparatus 10 using the above electrodes of 1 through 3 as a lowerelectrode, an etching process was performed by using a silicon oxidefilm (SiO₂) formed on the wafer W as a film to be etched. FIG. 15 showsa result of a matching position of a variable capacitor C1 of one of twovariable capacitors constituting a matching box 111 a during the etchingprocess.

Considering the result, “1. An electrode of a base member of Al” thatwas a standard electrode and “2. An electrode on which Al was sprayed ona base member of SiC” had similar matching positions of the matching box111 a. This indicated ways of flowing of a current that flows along thesurface of the lower electrode (the susceptor 100) when seen from plasmawere similar to each other. As a result, “2. An electrode on which Alwas sprayed on a base member of SiC” of the present embodiment indicatesthat the current sufficiently flew through the lower electrode asexpected as well as the standard of “1. An electrode of a base member ofAl.”

On the other hand, “3. An electrode without sprayed Al on a base memberof SiC” differed from “1. An electrode of a base member of Al” and “2.An electrode on which Al was sprayed on a base member of SiC” inmatching position and looked like a high-value resistance when seen fromthe plasma. This indicated that a way of flowing of the current thatflew along the surface of the lower electrode was different when seenfrom the plasma. This result shows that “3. An electrode without sprayedAl on a base member of SiC” of the present embodiment did not conductthe current through the lower electrode efficiently.

The above experimental result has proved that forming a conductive layerby spraying aluminum is necessary or preferable when SiC is used in abase member.

As mentioned above, a description was given of a substrate processingapparatus and a susceptor in the embodiments, but the substrateprocessing apparatus and the susceptor of the present embodiments arenot limited to the above embodiments, and various modification andimprovement could be made hereto without departing from the spirit andscope of the invention.

For example, in the above embodiments, the base member of the susceptorand the shower head is formed of SiC, but the material is not limited tothis as long as the base member is formed of ceramics. For example,aluminum nitride (AlN), alumina (Al₂O₃), silicon nitride (SiN) andoxidation zirconia (ZrO₂) may be used in the base member of thesusceptor and the shower head of the present invention.

In addition, for example, in the above embodiment, the susceptor and theshower head of the present invention is applied to the etchingprocessing apparatus. However, the susceptor and the shower head can bealso applied to plasma apparatuses other than the etching processingapparatus, for example, an ashing apparatus, a film deposition apparatusand the like. On this occasion, a capacitively coupled plasma (CCP:Capacitively Coupled Plasma) generation unit, an inductively coupledplasma (ICP: Inductively Coupled Plasma) generation unit, a helicon waveplasma (HWP: Helicon Wave Plasma) generation unit, a microwave-excitedsurface wave plasma generation unit including microwave plasma or SPA(Slot Plane Antenna) plasma that are generated from a radial antenna, anelectron cyclotron resonance plasma (ECR: Electron Cyclotron ResonancePlasma) generation unit and the like can be used as a unit to generateplasma in the plasma processing apparatus. Moreover, the susceptor ofthe present invention is available for a substrate processing apparatusthat processes a substrate by means other than plasma.

The substrate that is processed in the present invention is not limitedto the wafer W used in the description in the embodiments, but forexample, may be a large substrate for a flat panel display or asubstrate for EL (Electroluminescence) device or solar cell.

Furthermore, the cooling mechanism 102 a of the present invention allowsa fluid other than cooling water and Gulden to let through the pipes 102b as a coolant.

Thus, according to the embodiments of the present invention, temperatureresponsiveness of a susceptor can be improved.

All examples recited herein are intended for pedagogical purposes to aidthe reader in understanding the invention and the concepts contributedby the inventor to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions,nor does the organization of such examples in the specification relateto a showing of the superiority or inferiority of the invention.Although the embodiments of the present invention have been described indetail, it should be understood that various changes, substitutions, andalterations could be made hereto without departing from the spirit andscope of the invention.

What is claimed is:
 1. A substrate processing apparatus comprising: achamber; a susceptor to receive a substrate and provided in the chamber,the susceptor including a first ceramics base member including a flowpassage to let a coolant pass through and formed therein, a firstconductive layer formed on a principal surface and a side surface on asubstrate receiving side of the first ceramics base member, and anelectrostatic chuck stacked on the first conductive layer and configuredto electrostatically attract the wafer received thereon, wherein avolume of the flow passage is equal to or more than a volume of thefirst ceramics base member; a gas supply source to supply apredetermined gas into the chamber; and a high frequency power sourceconfigured to supply high frequency power to the first conductive layerto generate plasma from the predetermined gas and to treat the substrateby the plasma.
 2. The substrate processing apparatus of claim 1, whereinthe volume of the flow passage is 1 through 1.4 times as large as thefirst ceramics base member.
 3. The substrate processing apparatus ofclaim 1, wherein the first ceramics base member includes a step portionformed in a periphery thereof, and the step portion includes a pluralityof groove portions in a circumferential direction.
 4. The substrateprocessing apparatus of claim 3, wherein a thickness of the firstconductive layer formed on the principal surface and the plurality ofgroove portions is equal to or more than a skin depth determined basedon a frequency of the high frequency power.
 5. The substrate processingapparatus of claim 4, wherein the first conductive layer is formed intoa predetermined thickness in a range of 20 through 300 μm.
 6. Thesubstrate processing apparatus of claim 5, further comprising: an upperelectrode provided at a position facing the susceptor in the chamber,the upper electrode including a second ceramics base member and a secondconductive layer formed on a principal surface on an opposite side of asurface facing the susceptor and a side surface of the second ceramicsbase member, wherein the high frequency power source supplies the highfrequency power to the first conductive layer and the second conductivelayer.
 7. The substrate processing apparatus of claim 6, whereinresistances of the first conductive layer and the second conductivelayer are both equal to or less than 5×10⁻⁵Ω.
 8. The substrateprocessing apparatus of claim 1, wherein a first step portion is formedin the principal surface of the first ceramics base member in acircumferential direction, and the first ceramics base member is fixedwith a clamp that engages with the first step portion.
 9. The substrateprocessing apparatus of claim 8, wherein a second step portion is formedin the principal surface of the first ceramics base member in acircumferential direction, and a focus ring is engaged with the secondstep portion, and at least a part of the flow passage is formed in thefirst ceramics base member in a region overlapping with the focus ringwhen seen from a planar perspective in a stacking direction of the firstceramics base member and the focus ring.
 10. The substrate processingapparatus of claim 9, wherein a diameter of the receiving surface of thesusceptor defined by the second step portion in the principal surface ofthe first ceramics base member is smaller than that of the substrate,and a through-hole to let a pin for supporting the substrate passthrough is formed in the second step portion of the first ceramics basemember.
 11. The substrate processing apparatus of claim 1, wherein theelectrostatic chuck is stacked on the first conductive layer through oneof a sprayed layer and an adhesive layer.
 12. The substrate processingapparatus of claim 1, wherein the first ceramics base member is formedof one of silicon carbide (SiC), aluminum nitride (AlN), alumina(Al₂O₃), silicon nitride (SiN) and zirconia oxide (ZrO₃).
 13. Asusceptor comprising: a first ceramics base member including a flowpassage to let a coolant pass through and formed therein; a firstconductive layer formed on a principal surface and a side surface on asubstrate receiving side of the first ceramics base member; and anelectrostatic chuck stacked on the first conductive layer and configuredto electrostatically attract a substrate placed thereon, wherein avolume of the flow passage is equal to or more than a volume of thefirst ceramics base member.
 14. The susceptor of claim 13, wherein thevolume of the flow passage is 1 through 1.4 times as much as the volumeof the first ceramics base member.
 15. The susceptor of claim 13,wherein the first conductive layer is configured as an electrode towhich high frequency power is supplied, and the first conductive layeris thicker than a skin depth determined based on a frequency of the highfrequency power.